Thermal half-select printing matrix



INVENTOR JOHN 1.. JANNING gfi 4 WM- W HIS ATTORNEYS June 30, 1970 J.JANNING THERMAL HALF-SELECT PRINTING MATRIX Original Filed June 9, 1967FIG-.2

' 3,518,406 PatentedJune 30, 1970 United States Patent Otfice THERMALHALF-SELECT PRINTING MATRIX John L. Janning, Dayton, Ohio, assignor toThe National Cash Register Company, Dayton, Ohio, a corporation ofMaryland Original application June 19,1967, Ser. No. 646,888, now PatentNo. 3,466,423, dated Sept. 9, 1969. Divided and this application Nov. 8,1968, Ser. No. 774,391

Int. Cl. Hd I/00; G01d 15/00 U.s'. Cl. 219-216 2 Claims ABSTRACT OF THEDISCLOSURE matrix points which have coincident electrical currentflowing through crossing electrically resistive thermal printingconductors which define those points are disclosed. I v

CROSS-REFERENCE TO RELATED I p APPLICATION US. patent application Ser.No. 646,888, filed June 19, 1967, now Pat. No. 3,466,423, issued Sept.9, 1969, in the name of John L. Janning, inventor, of which this is adivision. i

BACKGROUND OF THE INVENTION "j Full-select thermal printing matricesemployed in the prior art must have an isolation diode for eachelectrical selection conductor that is employed in order to preventsneak currents and to isolate one'matrix element from another. Thethermal half-select printing matrices of the present invention eliminatethe necessity of supplying an isolation diode for each electricallyresistive thermal printing conductor of a thermal printing matrix.

SUMMARY Thermal half-select printing is accomplished by coincidentcurrent energization of electrically resistive thermal printingelements.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERREDEMBODIMENTS The thermal half-select printing matrices of the presentinvention are constructed for use with thermally sensitive recordmaterial. In the embodiment of FIG. 2, a thin electrically insulatingsubstrate 10, which may be of any electrically insulating material, suchas silicon dioxide, which is not subject to rapid heat diffusion from aheated point on the substrate, is employed. The thin electricallyinsulating substrate 10 should be on the order of one thousandth of aninch thick. The complete thermal printing member 11 is then mounted on arigid support board 13.

Electrically resistive thermal printing conductors which are on theorder of 16 thousandths to 70 thousandths of an inch wide and on theorder of 4 millionths of an inch thick, and which are composed of anelectrically resistive g and thefselection grounding'transistors 27 and29, which are selectively saturated when supplied with positive voltageselection signals on their bases. For example, if an electrical currentis passed through the column conducto'r 15coincidentally with anelectrical current through the row conductor 16, the radiated energy atthe matrix location 22 due to the current in each of the conductors 15and 16 will add, and, consequently, p'rintin'g'will occur on thethermally sensitive paper 31 at this location if the thermal thresholdof the thermally sensitive paper is exceeded. Energization of only oneconductor will not'produce sufiicient energy at a matrixlocation toexceed the thermal threshold of the thermally sensitive paper 31. Atother points of the matrix, such as the matrixpoints 24 and 26, whereonly the current through either a row conductor or a column conductorgenerates energy, the thermal printing threshold of the heat-sensitivepaper is not exceeded, and, therefore, printing does not occur at thesepoints.

The thermal printing paper 31 may be placed in proximity with theexposed side of the electrically insulating film substrate 10. Theoptimum operating characteristics are found to exist when theheat-sensitive paper 31 is positioned in its thermal printing positionand the current through a column conductor is increased until printingoccurs as the result of energy through the column conductor only. Thecurrent through the column conductor is then reduced by approximately10%. The same procedure is then followed for determining the optimumoperating point of a row conductor.

FIG. 1 shows another embodiment of the present invention, in which rowconductors 30 are secured on one side of an electrically insulatingsubstrate 28. The substrate 28 is then placed behind thenon-thermally-sensitive side of the thermally-sensitive paper 32. Columnconductors 36 of an electrically resistive material are secured on' oneside of another electrically insulating substrate 34; The substrate 34is positioned on the front, or heatsensitive, side of the thermallysensitive paper 32. As in the embodiment of FIG. 2, the row and columnconductors may be interchanged if desired. The row conductors 30 and thecolumn conductors 36 are selectively supplied separate and coincidentalelectrical currents by a current supply means, such as the currentsupply means 21 and 23 shown in FIG. 1. Just as in FIG. 1, if anelectrical current is passed through a column conductor 36coincidentally with a separate electrical current through a rowconductor 30, the thermal energy radiation from those portions of theelectrically resistive printing elements that intersect at a matrixlocation, like the matrix location 22 of FIG. 1, will be greater thanthe thermal energy radiation from those portions of the electricallyresistive printing elements that intersect but are not supplied withseparate and coincidental electrical currents. The foregoing greaterthermal energy radiation will be of a magnitude sufiicient to exceed thethermal threshold of the thermally-sensitive record material 32, causingprinting thereon in the same manner as in the FIG. 1 embodiment. Inparticular, printing will occur on the thermallysensitiverecord'rnaterial 32 in the vicinity of those thermal printing locationswhich are formed by an intersecting portion of a printing element 28 andan intersecting printing element 36 when both of the crossing printingelements 28 and 36 at a thermal printing location are supplied separateand coincidental electrical currents. The same procedure for obtainingthe optimum operating characteristics which was described in conjunctionwith the embodiment of FIG. 2 may also be employed in connection withthe embodiment of FIG. 1.

FIG. 3 shows an alternate electrically resistive conductor 17, which mayreplace the row conductors or'the column conductors of the embodimentsof FIGS. 1 and 2. This conductor 17 consists of alternate areas 19 of.an electrically conductive material, such as copper or gold, which aredeposited over an electrically resistive substrate material 18, such astin oxide, etc. The deposited conductive material 19 reduces theresistance along portions of the conductor 17 in which no print isdesired; therefore the total energy loss of the conductor 17 is reduced,and, in addition, printing is more accurately confined to the desiredprinting areas 25. External electrical connections are made to theconductive areas 37 and 39 by the conductive leads 41 and 43,respectively.

What is claimed is:

l. A thermal printing device for printing on a thermally-sensitiverecord material, comprising:

(a) a first set of electrically resistive printing elements,

(b) a second set of electrically resistive printing elements crossingthe first set of printing elements, to form a matrix of thermal printinglocations at those portions of the printing elements which interesect,

wherein the first set of electrically resistive printing elements ismounted on one side of a nonductive substrate, and the second set ofelectrically resistive printing elements is mounted on one side of asecond nonconductive substrate and is positioned to face the first setof electrically resistive printing elements, the thermally-sensitiverecord material being placed intermediate the two substrates, and (c)means to selectively supply a first electrical current through printingelements of the first set of electrically resistive printing elementsand a second separate and coincidental electrical current throughprinting elements of the second set of electrically resistive printingelements to cause thermal energy radiation from those portions of theelectrically resistive printing elements that intersect and are suppliedwith said first and second electrical currents to be greater thanthermal energy radiation from those portions of the electricallyresistive printing elements that intersect but are not supplied withboth of said first and second electrical currents,

said greater thermal energy radiation being of a magnitude exceeding thethermal threshold of the thermally-sensitive record material andeffecting printing thereon, said printing being effected on thethermally-sensitive record material, which is positioned adjacent thematrix of thermal printing locations, in the vicinity of those thermalprinting locations which are formed by an intersecting portion of aprinting element of the first set and an intersecting portion of aprinting element of the second set when both of the crossing printingelements at a thermal printing location are supplied said separate andcoincidental currents.

2. A thermal printing device as in claim 1 wherein the electricallyresistive printing elements of at least one of the sets of the printingelements each comprises an electrically conductive path of alternatelyarranged high-resistance portions and low-resistance portions, and thehighresistance portions define the thermal printing locations of thematrix.

References Cited UNITED STATES PATENTS 1,983,862 12/1934 Maness et al.2l9-544 2,610,102 9/1952 Gitzendanner et al.

2,686,222 8/1954 Walker et al. 346-166 X 2,869,965 1/1959 Willard 346743,043,988 7/ 1962 Hurvitz.

3,182,333 5/1965 Amada et al. 346-74 3,214,765 10/1965 Bond 34674 JOSEPHV. TRUHE, Primary Examiner P. W. GOWDEY, Assistant Examiner U.S. Cl.X.R.

